#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#include <stack>
#include <cmath>
#include <iomanip>

struct Point {
    Point() = default;

    Point(double x, double y) : x(x), y(y) {}

    double x = 0, y = 0;

    inline friend std::istream &operator>>(std::istream &istream, Point &point) {
        return istream >> point.x >> point.y;
    }

    inline friend std::ostream &operator<<(std::ostream &ostream, const Point &p) {
        return ostream << p.x << " " << p.y;
    }


    static double cross_product(const Point &A, const Point &B, const Point &C) {
        return (B.x - A.x) * (C.y - A.y) - (B.y - A.y) * (C.x - A.x);
    }
};

bool check(std::stack<Point> &stack, const Point &cnd) {
    Point p1 = stack.top();
    stack.pop();
    Point p2 = stack.top();
    stack.push(p1);

    return Point::cross_product(p2, p1, cnd) > 0;
}

int main() {
    std::ifstream input("infasuratoare.in");
    std::ofstream output("infasuratoare.out");

    int n;

    input >> n;
    std::vector<Point> points(n);
    Point ref(INT32_MAX, INT32_MAX);
    int pos = 0;
    for (int i = 0; i < n; ++i) {
        input >> points[i];

        if (ref.x > points[i].x) ref = points[i], pos = i;
        else if (ref.x == points[i].x) {
            if (ref.y > points[i].y) ref = points[i], pos = i;
        }
    }

    auto itr = points.begin() + pos;
    points.erase(itr);
    n--;

    std::sort(points.begin(), points.end(), [ref](const Point &lhs, const Point &rhs) {
        double cross = Point::cross_product(ref, lhs, rhs);
        if (cross != 0) return cross > 0;
        return (lhs.x - ref.x) * (lhs.x - ref.x) + (lhs.y - ref.y) * (lhs.y - ref.y) < (rhs.x - ref.x) * (rhs.x - ref.x) + (rhs.y - ref.y) * (rhs.y - ref.y);
    });

    std::stack<Point> stack;
    stack.push(ref);

    for (int i = 0; i < n; ++i) {
        while (stack.size() >= 2 && check(stack, points[i])) {
            stack.pop();
        }
        stack.push(points[i]);
    }
    output << stack.size() << "\n";
    output << std::setprecision(12) << std::fixed;
    std::stack<Point> aux;
    while (!stack.empty()) {
        aux.push(stack.top());
        stack.pop();
    }
    while (!aux.empty()) {
        output << aux.top() << '\n';
        aux.pop();
    }

    return 0;
}